SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e09cd37a0edde531ebd86a65b4b8662718e74b38d2940be608ae80788ad96c3' 
  AND token = 'Cb4PhrO6N7UVQn2VIraxeGiRVfdoPV4AEnHXurm6Zz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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