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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '00497cf787c1e829954e17d777c42da3a37af63207012745e0c7b6b197d9a033' 
  AND token = 'MY5762oI31JobOmff0TVlmmuFDIsHY6mbVGov7LOFQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}