SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b385628e57f4d93bd887685a954775ddde177c8a00e22054935973294fe876d8' 
  AND token = 'OAv8I560p1F2WYEUKeERIjRfGb3VT+TEPlkrtZbEMy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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