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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd5f0a4a6dad1847ce998cb6babcc938795c255d2a32c275003c06c145f8ece93' 
  AND token = 'BHU29Nhqm5TcTOmfXoDfKPWLQVQ4rnyMA7z5YUSF4HA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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