SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c46748099af6cd1895112e62bc3cff0dd929dd020958024443cf5bf649c271f2' 
  AND token = '98GoxaESaxYkgiVXV9Dk2VnGBDhasl4BRfMN9/h+5Ys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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