SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba4278b3b6da914ed0313e6f31b7fb519d5bd88be9729b0bbff853c12a5aca09' 
  AND token = 'RKl1cu59jJAoHesXSeJmkveDDV7lOSTTPuFpIVRwE6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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