SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d0f6654be82651cf6b3241b6030e67144d9ee035111f0c3be2e00e6851eee48' 
  AND token = 'n2a7rkTjQfgLhz8zJrZWBwhLl/AVMGouMmAwoKgU9Yw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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