SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e878991af5b80ab491b09bda863623548d700796a3caf0cec4b26109a8ec6462' 
  AND token = 'AqPEIHnudyztk0BrgU8rjh3VyMb0n0O4CCsTE4LfTHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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