SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8e7a47f53514b438106f1e9aaa873398c2a76b96d0fd2731735a01bd38ddcb9' 
  AND token = 'lyFOU3akyJ9pOu5khVQTiu5ixrLWlVLZUQqgWojfd2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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