SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2fc40b116b654612e1e4558f9dfa6357d7c73bca0f1ec495ec2cdfab0606161' 
  AND token = 'oQCDt+E9YsAqkgmajWQTF8OzzUlkya0AikMpC5YA1Ho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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