SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0440c4064ecb561eb2663746f6a0c5be586dc950776d94f353a81a3a8461072' 
  AND token = '7MaiOmgeByuwBU9EhZj2gIJ45MBIKHhlmGuvb2FcqiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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