SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b6c1f3d24ca549ff74a9ee567bbea755906e6ded867587cc933baaff5520b88' 
  AND token = '+JYNK4aRj7kzarvCnuvv6bFTABNX+Z/MuzELMz8GLpc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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