SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '264e20ab638edbc719425218393999cc6388b0d183d2109fc82d51957fe077bd' 
  AND token = 'UVzf2uZunIV/pg3MK1DfX45hfzGzZGRUKCbBgX6nUmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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