SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '549b420cefeecebd2dc73652e3d55d0497ad899baf743df967e844135d231ad7' 
  AND token = 'tUVmMBJvwtdOBaXTCW370Xy26oxDzJvEn405zgIjXo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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