SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e271e0de05a6ce381bad0e46052b494122c49580bd66df46c38dc59285c1f23' 
  AND token = '883pPPigOBJbUPMkaIEnOBeCzjzmE+BbcarNdG+3MzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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