SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9203956337126edb56557a2ba12b36562eb2903d8fcd0d38274882dd0b8c7501' 
  AND token = 'LtX+9/KKj5jBePAH0WzVGqntWjsK1tgSFOS+pMfDoBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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