SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3b7737e1ddda26945439f0ac61f5ecf241c3f5a6d64afab600804894a62d720' 
  AND token = 'zgwxFlYaDa9o9fjZtxY1l+XOFERvHWizLnZVPujdDTA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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