SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '593bd0316a7b6ca615379a3f66f1babbfee1c3a2c9703219f74016a3c0eaccd5' 
  AND token = 'JaDKB7tjA99XEJLhwjpIBzA/SiRbtjBxYWbXUK7iTR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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