SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b06c0418e2b963ae6693ea9f615fe36f6a898fecfacd0153a55119130e715418' 
  AND token = 'IfgIrsJaLpmcgjIq0sOslqXi78a/6OCsqRILatv+M6s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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