SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c50e2f8e2104e09574ab1b31deb6be881fe7a2c0e6504a3957b7e8cffc0c84a' 
  AND token = 'n6ceTjoEk1LegTl0CJ5PrdOymVjBalNwEFqW8Et907I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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