SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89a626d61e4d46480fdd70540857861955c13ac96a459af5c36effae5dcaa750' 
  AND token = 'IW6UsiZYkQj4+3fOXpPsmWjYcVkxlIeHHu7BF+/AaWA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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