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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f0408c2b0ef22dacb0b8196a51a200337ccf6d25defe26c9a682b99cf88cd31a' 
  AND token = '74SSpwEpOLxou2z9alRasZTY6wISbofpQRtuT3Noh5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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