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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e42cb589518c25ec1fbe064ed3ce095594e1aeb3f326b12dbf2f23c949593eef' 
  AND token = '16MOAzUgvWm5U2+xKXYryIfstcxDaezqpR4uWFguBmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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