SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a55973c2f7259166a061a45c5730311e258035cc2be454345e2a096ce93c92df' 
  AND token = 'ANXcLbReJLxXgDarynVPjEMEygZ1tFneiKGoV0DoFLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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