SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a03827a993fdda3a205fa272e3ef20353c7383cec9e499aeb95ec05d64da1128' 
  AND token = 'SUrwFoQiatDutGEQc0IIqnUid68ob4BddSt2OYlj+AY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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