SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c91ad43e1a8d4c221de0eff1ef7b379e238701ad0adb79353948ba2d2ba2bc5' 
  AND token = 'kxg8HLUigTn2wl1MkccH5P2PU+JdPmuaGXSlv0TL0Zw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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