SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8cf11b0aca4906497412668ce63657f87856cb76377a1928defb4c3e1b63ed6' 
  AND token = 'Rqb0/JZ1hKzgmDsklC4Y9NF9uGzM2LG6KdhXz2wD4pQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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