SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a3d513ebf3d560c0fa009746b507a1a3658111f23a34a165f93a8c22c61f328' 
  AND token = 'NvZR2RslYzmjAEwd/AMe7QPMZALIZ4ChmMYQWgM51e0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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