SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4378f5cf4305514ae278e1e8f73ce1b7733c3047d35e6798976219e8494b1fa' 
  AND token = 'ZbeNJQOP9tdRG2x/KYLVHh9dFHN7DJOBvTW+7Ip2QVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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