SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e813eecb57a5ddee2e2469c15b79fec7d539d8aadf83f41053be292dbead0598' 
  AND token = 'MSMcuCIPejfrnh6hkNVk53dHzCw2LxkMz3BRMpIUAwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}