SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a1f928a31da564ac91b37438afa052b84f8cd6ec778ac882ccf136ab0939db6' 
  AND token = '9M8uDBgU0YGLXdrsqOMlhNtfVC+Mcrxg7QAfe8SC0sE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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