SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c582c98590c618ac3a9792d1a590abdee8543f666e474e4781b80f47db786e63' 
  AND token = '3S9zzxG7VgAFvy6rzRhZYnO3zbjBeQfPML13TvHViaU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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