SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '950786cdba1f9df2c1fb4c36db6187f48b15c660357ffc58f0230ad5cdc07194' 
  AND token = 'T3uyx9V891keOBKXwy+PytwGp6uSE1x7i+AOFmkYBBI=' 
  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"
    }
  }
}