SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c8b2aed71ba59b013daa7a97d199310040c38c25e919e66f730f87c48bde651' 
  AND token = 'SUslxlakO+QOBK8SCDblJzsGrWLuVsgPKQJlxMksv0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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