SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c6c114f257a1b818118eacd4891c387c8c43d9a884f09502d27086d1a405fd3' 
  AND token = 'R4+jvuuPmLzWqnlAPjEKRcWTxCUV1PjDmaCefoeOIpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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