SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b48b71f0f718aaea9ab89facf085a412af630bac8a477f715a2413da659a5dd2' 
  AND token = 'xrJImwVbG8v7qPPE9TGzZAzUT6hyPH7frbmMf7nlKHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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