SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3344e0fc5f2e66009d3868250d898d52cfb34ab24b14e76fb6ebeab8c8ce0491' 
  AND token = 'u3tVfIqMH0jxm+AQwSdezpFG8sUPEA2Q0NfMD88Yp+8=' 
  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"
    }
  }
}