SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51f144d95f697e6b9a4b1191adec8900106eae7c38f03af1b6caeae93d58e4e6' 
  AND token = 'gp5QNQbExFqjjNDRncDusRehXGc8igm1k6cTZxze6dQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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