SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a799289452464eb78a74dac1417c0d184ecfcf4dcf371c676974cab17250a32' 
  AND token = 'exKixvpHgYT+vT5ns2CP/yp1IlbAsTP7XL1/CVLwz6s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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