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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a58f798dbbddcafb2cd41c37e6d7688f3c5695fe8cd43d8624a1c2d04f8a2f82' 
  AND token = 'F7/I/xL3pLeWclyyTzDzBK/IP/HWFDEcp3t2YMF1JKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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