SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfbcd778c30bbacb803ce69205eab4e36483d93e4f7e6056a0270499e658b2b7' 
  AND token = 'hr8LYk+UlcFcnTKv9MZ0h2kxVrmrdVOgR1pQwOxGgX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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