SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81512b7ab118c0ed0bec61421d9c19902aba41d2c4c0b6626d8e0edb572ef8c4' 
  AND token = 'hg5XCVIz/ZDIVW0+TUmLafFoZzuZ3/oH+tjBdpqsqGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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