SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0339a916850478c4af48c21d143a12d455ebd23168aa3f144898b036e2e5e3a7' 
  AND token = 'AF+Zz77wadg9msnPs4fvG6YuybWbrAfEV5Yfjwugx/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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