SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2bfdf92b8642511aa8c50c590b8015e385b26254958bdd7347846cf1f18b4d7' 
  AND token = 'f5UBonvVKEKLjak0qBAlNVicmO2HJmP15ebRgfmOI7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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