SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '72557b801e3f851da1626c58fae65f58603af68965cd3b4beb7cbced7210d7c1' 
  AND token = '7kf9xtuO4r+BWFz88usRxrKtB2g+DKpFD5QU2UNGsjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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