SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fda9734a9297778a5c9fa167fcca578be62e458683ff44f0883a84c3254f9a2' 
  AND token = 'GU4hrKSIuhMXO5w1BOCRQ+4jfmjhP0NG1tZ/nDoqCuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}