SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a567a98f23dda2d305ef6b9489653b3980546779b7ec49fe0c7ac23d245ab5a3' 
  AND token = 'BuUzZatIgaHB/Gsw4PuimFLZfB70CE6zHTR2+ApVAOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}