SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1399bc38640b6a62f2c118628c4349828d74c9f3430faac7abbf00e5d14f9fd9' 
  AND token = 'F4D2zHwG+eE/fO3hjsv0hhOYJogJVW1F58GzReejL14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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