SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f31cea5a6beece24d7ae1d6e8a900727a9479ddebe7ca3b2b4a570fe4f2a4c15' 
  AND token = 'fg3b8vjc5/HjbG3qt6p/Pl8JsvcyckR4vVKSLAijsf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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