SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '200342fc12c927dc38e73b5279c49b6bfe887e74106c16f522b90e52e6fda9a9' 
  AND token = '+IDMIxf75pht/HwO/IvmgzeuYUGE7XNvfR+wgJ4O2QE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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