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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e2c553d2bd7955ee674e18b37e6cc1541453b6c7875da12762eaf3595a89c41f' 
  AND token = 'cGyJRHCpZOit66oeysquyOOeQzkoqRIBIAg7Y0wtttc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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