SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a27c3892ee1994f668b11ee1f3d42134dc19540dfd385af57283123e52b5aa1' 
  AND token = '1sBVo6eCpVv24TSRLqMSEXh9RoEjtyXYUKb3kWMP0+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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