SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa5147d2103683cb16a567698aa0991fa1fa6e9e37481a60459e8c730b6593cd' 
  AND token = '6B8KnTTxaQ31ng3PzGYPWlSk+hpluAm0Df8Kf7Nou5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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