SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '339da09f9479325490f8be04f7e7efa59165907fec20a12ac0552cce34f28bdd' 
  AND token = 'ymYU3grCOAHCpHN73+x0o6KrJyIeb5PCkAeUZa4p8tY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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