SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '51f9752d81c786c55fd08c05a2c6abe38a9f097ff70303377e5619d1aba6fcec' 
  AND token = 'LNHjClwJGBTTg/aQ1ZhykiOpA4iSOy2bhgXQ2Mp5vW8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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