SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50035f750cd056a01519f52b5c3362a7ccdf8db6a597e7b6785824ebb1104b4a' 
  AND token = 'txCKq1w8CJPp/USKwiFFMpSQnCG+Tal9BWzUbh8Nscc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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