SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb8a4242a301aa8749107c662287e3056458b17df84cacdd2274b564aa2c01e3' 
  AND token = 'NRKvP8SJgyphcYbddAMgGYeF36dPJHQlYPV6jhIXiAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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