SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c482f35777f9a47d64e8762fac9352c3253b944a8bfb05b353310b6dc87dc88' 
  AND token = 'uMziATrGSxGzKELj7VUkiZvMMRZidx5cVyqnXZs/B44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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