SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1d73a460faf4b931ce5a83378e6894d264920dc00b14ee1fb96de93a9466379' 
  AND token = 'OSL9ZMT+uqjQhx51WGSYuxsGUOVBI/pbPMgfqbZzwtc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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